In traditional electric unmanned aerial vehicles, an amount of electricity of a battery can be prompted to a user in two ways: presenting a real-time voltage value of the battery, or presenting a real-time percentage of a remaining battery electricity.
Extensive experience is required to determine remaining electricity of a battery from a voltage value of the battery, thus only those skilled are able to determine a state of the battery from a voltage value of the battery. On the other hand, determining the remaining electricity of the battery by looking at a current electricity percentage is more intuitive. Either way, when the battery is in a low electricity state or an exhausted state, an alarm can be triggered. For example, an LED lamp can flash a red light, or a beeper can make a sound.
The conventional low voltage alarms are implemented by determining whether the battery reaches a preset low voltage value based on a fixed reference voltage value. For a beginning user of an unmanned aerial vehicle in aerial photography, an alarm for battery electricity cannot be received if the electric unmanned aerial vehicle flies to a remote position. In addition, it can be difficult to calculate the needed electricity for the electric unmanned aerial vehicle to return to an initial point from the present position. Consequently, the electric unmanned aerial vehicles may crash in a return trip, or be forced to return earlier than necessary, resulting in a lower battery utilization.